Starbucks CEO Howard Schultz is asking customers to no longer bring guns to the coffee chain, saying the presence of weapons in its stores is "unsettling and upsetting" to too many of its customers.

The request is not an outright ban. Customers who bring a gun will still be served, Schultz says. But it is a marked change in policy for the chain, which, up to now, simply respected state law on the issue. The vast majority of U.S. states allow the open carrying of firearms.

Starbucks and Schultz have generally taken a more progressive stance on public-policy issues, and the company's failure up to now to weigh in on the gun debate made it a lightning rod for both sides. Starbucks was criticized by gun-control advocates for not being more aggressive in making its stores gun-free and has faced a series of protests and boycott threats from liberal groups as a result.

At the same time, the company's stores have been the scene of several Starbucks Appreciation Day rallies by Second Amendment groups who have supported the company's previous neutral stance on the gun issue.

Schultz, in an open letter to customers, said those rallies "disingenuously" made it seem Starbucks supported states' open-carry laws. "To be clear: we do not want these events in our stores," he wrote.

However, while the request to not bring guns to Starbucks seems to favor gun-control advocacy, Schultz stressed he doesn't want Starbucks and its franchisees to be at the center of the fight any longer.

"We believe that gun policy should be addressed by government and law enforcement -- not by Starbucks and our store partners," he wrote.